The present invention is related to gears as typically found in machines. In particular, the present invention relates to gears having a wear indicator and an indicator viewing port whereby excessive wear in the gear can be realized prior to catastrophic failure.
The use of gears is a well known art. Gears are typically used to insure that two or more components move in concert with one another. Gears are known to progressively wear and it is known to be critical that the degree of wear be monitored such that the gears can be replaced prior to a catastrophic failure. One technique for inspection of wear is to disassemble the equipment for visual inspection of the gear teeth. This is time consuming and typically requires stopping the process utilizing the gear.
Various methods for providing a wear indicator system have been adopted. U.S. Pat. No. 5,451,110, for example, provides a chamber located in close proximity to a wear surface. The chamber is filled with a wear indicator which leaks onto the wearing surface upon rupture of the chamber. The wear indicator is a visual indication that wear is severe and that the part requires replacement. The technique has deficiencies in that it requires the wear indicator to migrate to an exterior location prior to detection. In a gear coupling with a low angular velocity, as used with parallel shafts for example, there may be no mechanical force sufficient for the material to migrate. This is particularly true if the gear is moving relatively slowly and centrifugal force is insufficient to force the material out of the gear coupling. Also if multiple gears are present in a close proximity the actual gear which is worn may be indeterminate and all of the gear couplings would have to be disassembled until the worn gear was located positively. Even then there may be multiple failures and locating a gear that is worn does not insure that others did not wear as well.
U.S. Pat. No. 4,650,441 provides an inspection port for viewing a modified gear tooth. While this technique has certain advantages, the major deficiency is the fact that the plug must be removed for inspection of the gear which adds maintenance items. This is undesirable.
Methods of measuring an electrical short circuit in a worn gear have been provided in U.S. Pat. Nos. 5,540,448 and 3,897,116. These require special equipment and training to inspect for wear which is undesirable. It is more advantageous to have a wear indicator which requires no special training and which can be monitored by visual inspection.
There still exist a need for a gear wear indicator which is rapid, convenient and which requires no additional tools or training to monitor. Such a device is provided by the present invention.
It is an object of the present invention to provide a gear wear indicator which is immediate and definitive.
It is another object of the present invention to provide a gear wear indicator which does not require any special tools or training.
A particular feature of the present invention is the fact that the gear wear indicator does not require any maintenance.
These and other advantages are provided in a gear comprising a gear wear indicator. The gear wear indicator comprises at least one indicator tooth where the indicator tooth comprises a cavity. An indicator element is located within the cavity and is visually altered when the cavity is ruptured. A viewing port is provided for viewing the indicator element in the cavity.
A preferred embodiment is provided in a gear comprising a gear wear indicator wherein the gear wear indicator comprises at least one indicator tooth. The indicator tooth comprises a cavity with an indicator element therein wherein the indicator element departs from the cavity when said cavity is ruptured. A viewing port is provided for viewing the cavity and determining if the indicator element has departed indicating the cavity has ruptured and the gear is worn.
Yet another preferred embodiment is provided in a gear comprising a gear wear indicator. The said gear wear indicator comprises at least one indicator tooth wherein said indicator tooth comprises a cavity. The cavity comprises an upper chamber and a lower chamber with a membrane between the upper chamber and lower chamber. When the cavity is ruptured a pressure difference between the cavities causes the membrane to rupture or deflect which is observed through a viewing port.